Mediation Server, Control Method Therefor, Communication Device, Control Method Therefor, Communication System, and Computer Program

ABSTRACT

A mediation server which is able to communicate with a plurality of account managing servers ( 104 ) and mediates requests for issuing subscription information transmitted from a plurality of communication devices between each communication device and any one of the plurality of account managing servers ( 104 ), the mediation server comprising, a selection unit configured to select the account managing server to which the request is to be transmitted based on information regarding a current operational status of each account managing server stored in a database, when the request is received from the communication device, and a transmission unit configured to transmit the request for issuing the subscription information to the selected account managing server.

TECHNICAL FIELD

The present invention generally relates to a mediation server, a controlmethod therefor, a communication device, a control method therefor, acommunications system and a computer program.

BACKGROUND

The use of downloadable USIM to establish the credentials of users andterminals is well known, and described in the 3GPP TR 33.812 V9.2.0. TR33.812 V9.2.0 discusses remote provisioning of subscriptions forMachine-to-Machine Equipment (M2ME). According to TR 33.812, M2ME, whichis a kind of a communication device, is provided with a temporaryprivate identifier called a Provisional Connectivity ID (PCID). The PCIDfollows the same format as an International Mobile Subscriber Identity(IMSI), and a network operator identified by the PCID is called aRegistration Operator (RO). The M2ME accesses the RO using the PCID, andrequests subscription information called a Machine CommunicationIdentity Module (MCIM). Upon request, the RO accesses another networkoperator called a Selected Home Operator (SHO), receives the MCIM issuedby the SHO, and forwards the MCIM to the M2ME.

In TR 33.812 V9.2.0, it is also described how a terminal can initiallyattach to a network using 3GPP radio technologies, receive an initialauthentication and authorization for a limited set of operations fromthe provider of the network to which the terminal is connected, and usethis limited authorization to trigger the authentication andauthorization of a connection to a provider of shared secrets,authorization certificates, and services which are attached to thesubscription of the user of the terminal, and download these into asecure area of the terminal, so that the shared secret andauthentication certificates can be used to authenticate and authorizethe terminals as being used under the subscription in question towardsthe network to which it is attached.

TR 33.812 describes several variations of the technology, which serve toenhance security, operability, and other factors. These include methodswhich leverage the presence of a UICC, as well as those which do notassume that such an entity is present.

TR 33.812 describes in general terms a mechanism by which a previouslyestablished credential can be used to authorize the establishment of aconnection through a visited operator with the home operator of thesubscriber, and there is an implicit assumption that there would only beone of each actor. However, this is not reflected in realisticscenarios, wherein a terminal will discover multiple radio networks, andattempt to authenticate itself with one of them. Since the network alsobroadcasts its identification, this network can be pre-selected, i.e.the terminal, by preference, addresses the authentication request to onenetwork, for instance one which the home operator of the subscriber hasa commercial relation with.

When there is no preference for the visited network, however, theterminal will attempt to establish a connection with the network whoseradio signals have the highest signal strength. While this situation maybe highly applicable in rural settings, it is increasingly such that incities, there are a number of mobile networks of equal signal strength.Hence, this criterion does not function well.

In such situations, a terminal acting in the scenario described in TR33.812 will select a network connection at random. This can be leveragedto address another concern, that of the network operator of the networkbeing flooded by connection requests from a very large number ofterminals at the same time enacting the scenarios in TR 33.812. Thiscould be the case, for example, when a service provider has decided tochange the SHO for a fleet of power meters. All M2MEs would be receivingBootstrap requests simultaneously and thus all would try to connect tothe RO in the same instant.

SUMMARY

The present invention is intended to address the above-describedproblem, and it is a feature of the present invention to introduce animproved technology for providing a communication device withsubscription information via a network.

Note that “subscription information” is also referred to as the MCIM inthe present application.

According to the first aspect of the present invention, there isprovided a mediation server which is able to communicate with aplurality of account managing servers and mediates requests for issuingsubscription information transmitted from a plurality of communicationdevices between each communication device and any one of the pluralityof account managing servers, the mediation server comprising, aselection unit configured to select the account managing server to whichthe request is to be transmitted based on information regarding acurrent operational status of each account managing server stored in adatabase, when the request is received from the communication device,and a transmission unit configured to transmit the request for issuingthe subscription information to the selected account managing server.

According to the second aspect of the present invention, there isprovided a communication device which is able to request an issuance ofsubscription information to one of a plurality of account managingservers via a mediation server according to the first aspect of thepresent invention, the communication device comprising, a storage unitconfigured to store at least two items of identification informationeach having a different priority, and a communication unit configured totransmit the request of the issuance of the subscription information tothe mediation server, wherein the communication unit is furtherconfigured to transmit the request with the identification informationof a lower priority until the request is sequentially rejected apredetermined number of times, and after the request is sequentiallyrejected the predetermined number of times, to transmit the request withthe identification information of a higher priority.

According to the third aspect of the present invention, there isprovided a communication system comprising a plurality of accountmanaging servers and a mediation server which is able to communicatewith a plurality of account managing servers and mediates requests forissuing subscription information transmitted from a plurality ofcommunication devices between each communication device and any one ofthe plurality of account managing servers, wherein the mediation servercomprising, a selection unit configured to select the account managingserver to which the request is to be transmitted based on informationregarding a current operational status of each account managing serverstored in a database, when the request is received from thecommunication device, and a transmission unit configured to transmit therequest for issuing the subscription information to the selected accountmanaging server, the selected account managing server which receives therequest from the mediation server issues the subscription informationand transmits the subscription information to the mediation server, andthe mediation server transmits the subscription information to thecommunication device.

According to the fourth aspect of the present invention, there isprovided a control method of a mediation server which is able tocommunicate with a plurality of account managing servers and mediatesrequests for issuing subscription information transmitted from aplurality of communication devices between each communication device andany one of the plurality of account managing servers, the methodcomprising steps of, selecting the account managing server to which therequest is to be transmitted based on information regarding a currentoperational status of each account managing server stored in a database,when the request is received from the communication device, andtransmitting the request for issuing the subscription information to theselected account managing server.

According to the fifth aspect of the present invention, there isprovided a control method of a communication device which is able torequest an issuance of subscription information to one of a plurality ofaccount managing servers via a mediation server according to the firstaspect of the present invention, the communication device comprising astorage unit configured to store at least two identification informationeach having a different priority, the method comprising steps of,transmitting the request of the issuance of the subscription informationto the mediation server, with the identification information of a lowerpriority until the request is sequentially rejected a predeterminednumber of times, and after the request is sequentially rejected thepredetermined number of times, transmitting the request with theidentification information of a higher priority.

According to the sixth aspect of the present invention, there isprovided a computer program which causes a computer to execute a controlmethod of a mediation server which is able to communicate with aplurality of account managing servers and mediates requests for issuingsubscription information transmitted from a plurality of communicationdevices between each communication device and any one of the pluralityof account managing servers, the method comprising steps of, selectingthe account managing server to which the request is to be transmittedbased on information regarding a current operational status of eachaccount managing server stored in a database, when the request isreceived from the communication device, and transmitting the request forissuing the subscription information to the selected account managingserver.

According to the seventh aspect of the present invention, there isprovided a computer program which causes a computer to execute acommunication device which is able to request an issuance ofsubscription information to one of a plurality of account managingservers via a mediation server according to the first aspect of thepresent invention, the communication device comprising a storage unitconfigured to store at least two identification information each havinga different priority, the method comprising steps of, transmitting therequest of the issuance of the subscription information to the mediationserver, with the identification information of a lower priority untilthe request is sequentially rejected a predetermined number of times,and after the request is sequentially rejected the predetermined numberof times, transmitting the request with the identification informationof a higher priority.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings, in which like reference characters designate the sameor similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an overview of a provisioning system 100 according toone aspect of embodiments of the present invention;

FIG. 2A is a functional block diagram of the mediation server 103;

FIG. 2B is a functional block diagram of the communication device 101;

FIG. 3 is an example of data table stored in the connection DB 206;

FIG. 4 is a sequence diagram illustrating an account provisioningprocedure according to one aspect of embodiments of the presentinvention;

FIG. 5 is another example of data table stored in the connection DB 206;

FIG. 6 is a sequence diagram illustrating an retry attempt by thecommunication device 101 to the base station 102 according to anotheraspect of embodiments of the present invention; and

FIG. 7 is an example of data table stored in the PCID table 213 of thecommunication device 101.

DETAILED DESCRIPTION

FIG. 1 illustrates an overview of a provisioning system 100 according tothe first embodiment of the present invention. In FIG. 1, communicationdevice 101 is a device for communicating with a visited network operator(VNO) 102 and a mediation server 103 as a registration operator (RO),and contains a Provisional Connectivity ID (PCID). Examples of thecommunication device 101 include a mobile terminal, a digital photoframe, and a monitoring sensor. Because the PCID identifies thecommunication device 101, the PCID can be used as device identificationinformation for identifying the communication device 101. Thecommunication device 101 is intended to obtain a Machine CommunicationIdentity Module (MCIM) of a Selected Home Operator (SHO) as subscriptioninformation. Although the communication device 101 corresponds toMachine-to-Machine equipment (M2ME) described in TR 33.812, the term“communication device” is used in place of the term “M2ME” because thecommunication performed by the communication device 101 is not limitedto machine-to-machine communication.

The communication device 101 comprises a control unit 211, acommunication unit 212 and a PCID table. It should be noted that thefunctionality of each block in the communication device 101 may beimplemented using dedicated hardware, using software executed by aprocessor (not shown), or a combination thereof.

A base station 102 provides temporary 3GPP network access to thecommunication device 101, where authentication using credentials such asa PCID may be required. Although the base station 102 is illustrated asa single node, the functions of the mediation server 103 may beseparated into two or more nodes. The base station is operated byvisited network operator (VNO). The base station 102 supports thefollowing functions.

-   -   Provide temporary 3GPP network access to the communication        device 101, where authentication using credentials such as a        PCID may be required. The base station may provide full or        restricted connectivity during initial access.    -   Provide open network access to the Discovery and Registration        Function (DRF) when possible, i.e., where no credentials or        authentication are required for this access. This function        applies when the VNO will become the SHO after registration and        provisioning, for example.    -   Provide connectivity to the SHO, when the SHO and the VNO are        distinct operators.

The mediation server 103 is a server for providing the communicationdevice 101 with the MCIM of any one of the SHO 1 to SHO3. The purpose ofthe mediation server 103 is to provide initial connectivity to thecommunication device 101 and to provide registration and provisioningfunctions for the communication device 101. This typically involves theInitial Connectivity, Discovery and Registration, and MCIM Download andProvisioning Functions. Although the mediation server 103 is illustratedas a single node, the functions of the mediation server 103 may beseparated into two or more nodes. The mediation server 103 is operatedby the Registration Operator (RO), which is identified by the PCID andserves the communication device 101 to enable the communication device101 to access to a 3GPP network in order to obtain the MCIM.

An account managing servers 104A to 104C are servers for managing theaccount information such as the MCIM. Although each of the accountmanaging servers 104A to 104C is illustrated as a single node, thefunctions of the account managing server 104 may be separated into twoor more nodes. The account managing server 104 is operated by the SHO.

An authentication servers 105A to 105C are servers for validating thecredentials used to verify the communication device 101 as a trustedplatform. The authentication server may also issue these credentials.Although each of the authentication servers 105A to 105C is illustratedas a single node, the functions of the authentication server 105 may beseparated into two or more nodes. The authentication server 105 isoperated by the Platform Validation Authority (PVA). The authenticationserver 105 supports the following:

-   -   Validation of platform credentials that assert the authenticity        and integrity of the communication device 101 as a platform to        hold the MCIM application and credentials;    -   Providing the DPF and SHO with information related to the        success or failure of the validation of the communication device        101.        -   Obtaining new platform credentials when required, e.g.,            after a remote update of the communication device 101.

FIG. 2A is a functional block diagram of the mediation server 103. Themediation server 103 comprises an initial connectivity function (ICF)201, a MCIM download and provisioning function (DPF) 202, a discoveryand registration function (DRF) 203, connection quota manager (CM) 204,a connection recommendation function (CRF) 205 and a connection DB 206.The detailed operations of each functional block in the mediation server103 will be described later with reference to the sequence diagram ofFIG. 4.

The ICF 201 provides connectivity services (at layers above the basicnetwork access provided by the VNO) to help with the post-purchasediscovery of the SHO. The ICF 201 provides IP connectivity for thecommunication device 101 to request downloading and provisioning of MCIMcredentials and applications from a DPF via a Visited Network Operator(VNO) network.

The DPF 202 is a function for managing the downloading and provisioningof the MCIM applications and credentials to the communication device101. In order to perform the secure provisioning of the MCIMapplications and their parameters to the communication device 101, theDPF needs to support functions specified in 3GPP TR 33.812 V9.2.0.

The DRF 203 helps the communication device 101 to discover and registerwith any one of the account managing servers 104A to 104C. Addressresolution is included within DRF 204.

The CM 204 acts as a queue management function. It uses factorsinfluencing the speed of MCIM allocation, such as the load on eachaccount managing server 104, i.e., how many communication devices areattached to each account managing server 104, to determine to whichaccount managing server 104 a communication device 101 will beallocated. In a 3GPP standardized core network, this would be equivalentto knowledge about the load on the HSS. This information can becollected by the Operations and Management system of the Core Network,by a standardized system such as SNMP or OMA DM, or similar. Theinformation is sent to the mediation server 103 either periodically orin real-time, for instance using the IMS Presence mechanism. In thatcase, an intermediary entity may be required to collect and filter theinformation before distributing it to the different mediation server103.

When the communication device 101 sends an attach request to themediation server 103, the CM 204 allocates the communication device 101to the most appropriate account managing server 104. This may depend onwhich account managing server 104 is at the least loaded status. If therequest for MCIM is to be sent to the least loaded account managingserver 104, the CM 204 looks up the load, and stores the informationabout which account managing server 104 the communication device 101 wasconnected to in the Connection DB 206. The allocation is done based onthe PCID of the communication device 101 and the load on the accountmanaging server 104.

If the allocation is not done based on the load but some other factor,such that the mediation server 103 has a fixed number of MCIM allocatedfrom each account managing server 104, the mechanism will be the same,except that the number of MCIM is used to determine which accountmanaging server 104 is the most appropriate. More complex mechanisms canalso be applied, such as calculations of price over capacity and thelike.

If the communication device 101 has several installed MCIM, themediation server 103 can facilitate the selection between them byassigning an appropriate account managing server 104. In cases wherePCIDs indicating a priority are used during the attachment procedure,the CM 204 puts requests made using a higher priority PCID in front ofrequests made with a lower priority PCID in a request queue.

The CRF 205 is a recommendation function to provide a recommendation ofthe account managing server 104 which is the most likely to accept arequest of issuance of the MCIM, in response to a query from the CM 204.The CRF 205 retrieves status information of each account managing serverin the connection DB 206 and determines the most recommendable one forthe communication device to obtain the MCIM immediately.

The connection DB 206 stores status information of respective accountmanaging servers 104. The connection DB 206 may be a part of themediation server or may be located on an external network and connectedto the mediation server 103. An example of the data table stored in theconnection DB 206 is illustrated in FIG. 3. Entries in the statusinformation table shown in FIG. 3 include identification information(ID) 301 of each account managing server 104 and time information of T1(302) and T2 (303). The ID 301 may include any kind of information whichpermits unique identification of the account managing server 104, forexample, it may be an International Mobile Subscriber Identity (IMSI) ofeach account managing server 104. T1 (302) indicates a start time ofrequest for issuance of the MCIM to the account managing server 104operated by the SHO identified by the ID 301. T2 (302) indicates areception time of the issued MCIM from the account managing server 104operated by the SHO identified by the ID 301. A difference between theT2 and T1, that is T2−T1, indicates a response time period for issuingthe MCIM by the account managing server 104 in response to the MCIMissuance request from the mediation server 103 to the account managingserver 104. The difference can indicate an operation status, that is,the performance of the corresponding account managing server 104.Therefore, a bigger difference indicates lower performance and a smallerdifference indicates higher performance.

FIG. 4 is a sequence diagram illustrating an MCIM provisioning procedureaccording to an embodiment of the present invention.

In step S401, AKA authentication between the communication device andthe ICF 201 in the mediation server 103 via the base station 102 isexecuted according to the process defined in the 3GPP TR33.812, V9.2.0.In step S402, the ICF 201 requests the DRF 203 to bootstrap. Internally,in the mediation server 103, the PCID and the IP address of thecommunication device 101 are forwarded from the ICF 201 to the DRF 203.

In step S403, according to the PCID-IMSI, the DRF 203 queries theaddress of the DPF 202 and the SHO in its database. Then the DRF 203generates the Bootstrap message. In step S404, the DRF 203 sends theBootstrap message to the communication device 101. In the message theDRF 203 includes the IP connectivity parameters (NAPDEF), the address ofthe DPF 202 (Server URL), the context of the MCIM application provisionand the context of the M2M application provision. If the providedPCID-IMSI already points to the mediation server 103, the mediationserver 103 can become the SHO, in which case, those accessing themediation server 103 continue using the same IMSI.

In step S405, triggered by the Bootstrap message, the communicationdevice 101 contacts the DPF 202 and includes relevant information of thecommunication device 101 and the TRE (e.g., platform validation info).In step 406, DPF 202 sends a request to the CM 204 for an accountmanaging server 104 which is the most appropriate for issuing the MCIMas soon as possible for the communication device 101.

In step S407, the CM 204 queries the CRF 205 for information about whichaccount managing server 104 is most likely to be able to accept therequest under the current conditions. The CRF 205 selects one of theplurality of account managing servers 104 with reference to theconnection DB 206. When the connection database stores time informationof T1 (302) and T2 (303), the CRF calculates the differences between T2and T2 for each account managing server 104 identified by the ID 301 andcompares the calculated differences to find the one having the minimumvalue.

The account managing server 104 which has the minimum value can beconsidered the most appropriate server having a higher performance thanthe others for requesting the issuance of the MCIM for the communicationdevice 101. In step S409, the CRF 205 sends a response to the query fromthe CM 204 with the address of the account managing server 104 which isselected as recommendable in S408. The account managing server 104 has aunique identifier, which can be based on the IMSI or other specificidentifier including IP address or URI, and is stored in the connectiondatabase 206. In step S410, the CM 204 informs the recommendable accountmanaging server 104 with its address to the DPF 202. In step S411, theDPF 202 connects to the recommended account managing server 104 usingthe address informed it by the CM, and relays the information of thecommunication device 101 and TRE there. In step S411, the DPF alsorecords the time when it transmits the request to the account managingserver 104 as T1 to be stored in the connection DB 206.

In step S412, the account managing server 104 sends the validation infosigned by the PfC and TRE identity to a authentication server 105associated with the account managing server 104 and requests theauthentication server 105 to validate the authenticity and integrity ofthe TRE. In step S413, the authentication server 105 locally validatesthe authenticity and integrity of the communication device 101,according to the requirements of the account managing server 104.

In step S414, the authentication server 105 sends the validation resultsback to the account managing server 104, according to requirements fromthe account managing server 104. The account managing server 104encrypts the MCIM by using the PfC and generates the management objectfor the communication device 101 (e.g., MCIMobj).

In step S416, the account managing server 104 delivers the encryptedMCIM (e.g., within MCIMobj) to the DPF 202 and authorizes provisioningof the MCIM application to the communication device 101. In S416, theDPF records the time when it receives the MCIMobj from the accountmanaging server 104 as T2 to be stored in the connection DB 206.

In step S417, the DPF 202 downloads a MCIM object to the communicationdevice 101 and the communication device 101 provisions the downloadedMCIM into the TRE. The TRE decrypts MCIMobj by using the TRE PlatformKey to obtain the MCIM. The communication device 101 reports thesuccess/failure status of the provisioning to the DPF 202. In step S418,the DPF 202 updates the connection DB 206 with the recorded timeinformation T1 and T2.

In the above embodiment, the CRF 205 selects the account managing server104 based on the current performance of each server determined using theresponse time. However, the embodiments of the present invention are notlimited to this. For example, when the connection DB 206 stores thestatus information of each server regarding busy period 502, as shown inFIG. 5, the CRF 205 may select a server which is not in the busy statebased on the contents in the connection DB 206. If there exist two ormore account managing servers 104 which are not in the busy state, theCRF 205 may further consider the response time based on the differenceof T2 and T1 also stored in the connection DB 206 as shown in FIG. 3 andthe account managing server 104 having the minimum difference value maybe selected.

It is furthermore possible to use any type of performance parameterwhich can be used to identify a server that having higher performancethan others and to store such a performance parameter in the connectionDB 206.

For example, using the SLA Management Handbook Volume 3, Service andTechnology Examples, published from TeleManagement Forum, July 2004, thestatus information relating to the account managing servers 104 mayinclude at least any one of service and server performance parametersand latencies or delays caused by the intermediary networks, such asperformance specific parameters measured in ATM, SDH, Frame Relay, etc.;layer parameters; service operational parameters such as percentage ofmemory available, number of simultaneous processes, etc.; andService/Technology Independent Parameters, such as percentageavailability, Mean Time Between Failures (MTBF), Outage Intensity (OI),Mean Time to Provision Service (MTPS), and Mean Time to Restore Service(MTRS).

For further examples, according to the KPI in OMA Requirements Document(“Key Performance Indicator for OMA Enablers Requirements, Draft Version1.0—22 Mar. 2010, Open Mobile Alliance,OMA-RD-KPIinOMA-V1_(—)0-20100322-D”), performance indication parametersmay be at least any one of measurement on sessions (e.g., parallelworking session) of a service, respond delay for a service, and thetraffic load for a service, if such information is available.

According to the above embodiment, when a mediation server 103, forinstance acting in the role of a connectivity broker, has a number ofcommunication devices 101 which need to connect to the network and henceneed to be allocated with an MCIM, the invention will be useful. Thisscenario occurs, for example, when there are a large number ofcommunication devices which connect for the first time, when thecommunication device need to refresh their MCIM at the same time, orwhen the communication device need to change the SHO (among the SHOwhich the RO has agreements with).

The first case will occur, for example, when a new housing developmentis switched on, and all the smart meters as the communication devices101 in the houses connect for the first time. The second case will occurwhen the communication device has been inactive for a long time, forinstance when they are intended to monitor an earthquake (in which casethey will be inactive until an earthquake actually occurs). The thirdcase will occur when the mediation server 103 (RO) sees a need to changethe home operator for the communication device 101, perhaps because thecontracts have expired.

This scenario assumes that the communication devices are attempting toconnect and report data periodically, rather than constantly.Furthermore, it assumes that the reporting is not real-time, but can beperformed in batches. This scenario assumes that the terminals canattach to one of several account managing servers (SHOs), which areresponsible for the generation of the MCIM. The mediation server 103then selects the most appropriate one for the communication device 101,based on several factors including the current load based on theprocessing time measured using T1 and T2 as shown in FIG. 3).

Whether the mediation server 103 can receive load data is a businessdecision on the part of the account managing server 104, and may betaken by the SHO organization, or outsourced to a hosting organization(e.g. when the SHO is running a network operated by a different party,such as a service organization).

FIG. 6 is a sequence diagram illustrating a retry attempt by thecommunication device 101 to the base station 102 according to anembodiment of the present invention. The control unit 211 of thecommunication device 101 has a connection managing function forexecuting an exponential back-off algorithm in case of attachmentfailures. In FIG. 6, when an attach request from the communicationdevice 101 to the base station 102 fails a predetermined number oftimes, for example twice in a case illustrated in FIG. 6, thecommunication device switches the PCID attached to the request.

FIG. 7 shows an example of the PCID table 213 in the communicationdevice 101. In the case shown in FIG. 7, the PCID table stores twodifferent PCIDs each having different priority. The PCID 1 has a lowerpriority and the PCID 2 has a higher priority. However, it should benoted that the number of the PCIDs which the communication device 101can use may not be limited to two.

In step S601 and S603, the communication device 101 tries to attach tothe base station 102 using the PCID 1 having the lower priority. If theattach request is successfully received by the base station, the processproceeds to step S401, as depicted in FIG. 4. However, if the attachrequest to the base station 102 using the PCID 1 fails twice and thecommunication device receives a rejection from the base station 102 inS604, after the rejection in S602, the communication device waits for apredetermined time period Tw and retries attaching to the base station102 using the PCID 2 having the higher priority.

The base station 102 receives the attach request from the communicationdevice 101 with the higher priority PCID, it accepts the attach requestin S606. The base station 102 can identify the PCIDs with higherpriority and since the mechanism for identifying these kinds of PCIDs bythe base station 102 may be that commonly used in the technical art, adetailed description is omitted from this specification.

As a further embodiment of the present invention regarding proceduresaccording to FIG. 4, only if the DPF 202 receives contact from thecommunication device 101 in S405 using the PCID having higher priority,does it send a request for the recommendation of the account managingserver 104 to the CM 204 in step S406. The CM 204 maintains a requestqueue for requesting from a plurality of communication devices 101. Ifthe CM 204 receives a request with a PCID having higher priority, the CM204 prioritizes the request with the PCID of higher priority over otherrequests with PCIDs of lower priority included in the request queue,similar to a queue management system for QoS.

The embodiment relating to FIGS. 6 and 7 is useful in the followingsituation. For the communication device 101 which can report data eitherin batches or real-time, however, a mechanism is needed to overcome thelimitation that a device may not be able to deliver data urgently, sinceall connection slots in the available network have been occupied byother devices reporting in batch. This is somewhat similar, but notequivalent, to the mechanism of emergency call establishment in GSM.However, the main difference here is that the data is urgent, but not anemergency—for instance, relating to an increase in traffic over abridge, rather than the general statistics of the traffic, and not anemergency (the traffic is moving, there is just more of it).

Furthermore, some connection requests may be more urgent than others.For example a daily update of a power meter reading is less urgent than,e.g., a surge in automobile traffic at a bridge, tunnel or the like. Inorder to distinguish between more urgent and less urgent connections, ifthe communication device 101 has at least two PCIDs available eachindicating a different priority class, depending upon the situation, oneor the other PCID may be used when attaching to the network. Thecommunication device 101 can be attached having used the low priorityPCID when suddenly the necessity for an urgent update arises. To avoidthe possibility of continuous rejection of the connection, the currentMCIM can be detached from the network and a new connection can berequested with a PCID indicating a higher priority.

When there is a desire to prioritize allocating MCIM to some devicesover others, the communication device 101 can have several PCIDs whichcan be divided into groups with different priorities. When there is anurgent need to connect, a separate PCID can be used by the communicationdevice 101. It is possible to envision several PCID being allocated toterminals for establishment of connection at various levels of urgency.

The selection of the appropriate PCID would be managed by the connectionmanaging function in the control unit 211 of the communication device101, which hence would have to be aware of the urgency of thetransmission. This, then, in turn assumes a certain level ofpreprocessing before the transmission in the communication device 101,which can be achieved by the device being equipped with some processingand memory, something it would need anyway to process data to bereported periodically.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

1. A mediation server, comprising: a selection unit configured such that, in response to the mediation server receiving a request for issuing a downloadable SIM transmitted from a communication device, the selection unit selects from a set of two or more account managing servers an account managing server to which the request is to be transmitted based on information stored in a database regarding a current operational status of each account managing server included in said set; and a transmission unit configured to transmit the request for issuing the downloadable SIM to the selected account managing server.
 2. The mediation server according to claim 1, further comprising: an updating unit configured to update the information stored in the database based on a time period between the transmission of the request to the selected account managing server and reception of the downloadable SIM from the selected account managing server.
 3. The mediation server according to claim 2, wherein the selection unit is further configured to select such an account managing server that has a time period shorter than those of other account managing servers.
 4. The mediation server according to claim 1, wherein the database manages information regarding busy time period for each account managing server, and the selection unit is further configured to select such an account managing server that does not have a busy status at the time of selection based on the stored information in the connection database.
 5. The mediation server according to claim 1, wherein the information regarding the current operational status includes one or more types of performance parameters respectively indicating a current performance of the account managing server, and the selection unit is further configured to select such an account managing server that has higher performance than other account managing server based on comparison of values of the performance parameters.
 6. The mediation server according to claim 1, wherein a communication device issues the request using one of at least two items of identification information of the communication device, each having different priority, and the mediation server further comprising: a queue management unit configured to receive requests from the communication devices and to transfer the requests to the selection unit by managing a queue of requests based on the identification information attached to each request, wherein the queue management unit is further configured to transfer the request with the identification information of higher priority, prior to the request with the identification information of lower priority in the queue.
 7. A communication device which is able to request an issuance of downloadable SIM from one of a plurality of account managing servers via a mediation server, the communication device comprising: a storage unit configured to store at least two items of identification information each having a different priority; and a communication unit configured to transmit a request for the issuance of the downloadable SIM to the mediation server, wherein the communication unit is further configured to transmit the request with the identification information of a lower priority until the request is rejected a predetermined number of times, and after the request is rejected the predetermined number of times, to transmit the request with the identification information of a higher priority.
 8. A communication system comprising: a plurality of account managing servers; and a mediation server which is able to communicate with each of said plurality of account managing servers, wherein the mediation server comprises: (i) a selection unit configured such that, in response to the mediation server receiving a request for issuing a downloadable SIM transmitted from a communication device, the selection unit selects from the plurality of account managing servers an account managing server to which the request is to be transmitted based on information stored in a database regarding a current operational status of each account managing server included in said plurality; and (ii) a transmission unit configured to transmit the request for issuing the downloadable SIM to the selected account managing server, the selected account managing server is configured to transmit the downloadable SIM to the mediation server in response to receiving the request from the mediation server, and the mediation server is configured to forward the downloadable SIM to the communication device.
 9. A method performed by a mediation server, the method comprising: the mediation server receiving from a communication device a request for issuing a downloadable SIM; the mediation server, in response to receiving the request, selecting from a set of two or more account managing servers an account managing server to which the request is to be transmitted, wherein the selection of the account managing server is based on information stored in a database regarding a current operational status of each account managing server included in said set of account managing servers; and the mediation server transmitting the request for issuing the downloadable SIM to the selected account managing server.
 10. A control method performed by a communication device the communication device comprising a storage unit configured to store a first identifier associated with a first priority and a second identifier associated with a second priority, wherein the second priority first priority, the method comprising: (a) the communication device transmitting a request for the issuance of a downloadable SIM to a mediation server, the request including the first identifier; (b) the communication device receiving an indication that the request has been rejected; (c) the communication device, in response to receiving the indication, determining the number of times the request has been rejected; (d) after step (c), the communication device performing one of: (d1) transmitting the request again and (d2) transmitting a new request for the issuance of the downloadable SIM, wherein the new request includes the second identifier, wherein the communication device is configured to perform step (d1) rather than step (d2) in response to determining that the number of times the request has been rejected is less than a predetermined number, and the communication device is configured to perform step (d2) rather than step (d1) in response to determining that the number of times the request has been rejected is greater than the predetermined number.
 11. A computer program product comprising a computer readable medium storing a computer program which, when executed by a computer, causes the computer to perform the steps of: selecting from a set of two or more account managing servers an account managing server, wherein the selection of the account managing server is based on information stored in a database regarding a current operational status of each account managing server included in said set of account managing servers, wherein the selecting step is performed in response to the computer receiving from a communication device a request for issuing a downloadable SIM; and transmitting the request for issuing the downloadable SIM to the selected account managing server.
 12. A computer program product comprising a computer readable medium storing a computer program which, when executed by a computer, causes the computer to perform the steps of: (a) transmitting a request for the issuance of a downloadable SIM to a mediation server, the request including a first identifier associated with a first priority, (b) processing a response to the request to determine whether the request has been rejected; (c) in response to determining that the response has been rejected, determining a number of times the request has been rejected; (d) after step (c), performing one of: (d1) transmitting the request again and (d2) transmitting a new request for the issuance of the downloadable SIM, wherein the new request includes a second identifier associated with a second priority that is higher than the first priority, wherein the computer program is configured to cause the computer to perform step (d1) rather than step (d2) in response to the computer program determining that the number of times the request has been rejected is less than a predetermined number, and the computer program is configured to cause the computer to perform step (d2) rather than step (d1) in response to the computer program determining that the number of times the request has been rejected is greater than the predetermined number. 